Ocean Acidification

The sea is a complex chemical soup containing proteins, salts and minerals – all held in balance or “buffered” between being too acid and too alkaline by naturally occurring chemical reactions. These buffering reactions allow the sea to absorb carbon dioxide from the atmosphere and the tiny plants living in the oceans to break it down into sugars to feed their own bodies and to oxygen. In fact, the sea is the largest converter of carbon dioxide to oxygen on this planet – many times more powerful than all the plants in the rain forests of South America put together.

When too much carbon dioxide ( CO₂) dissolves in water (H₂O) it converts the carbonate (CO₃²) that animals and tiny marine plants use to make their shells to bicarbonate (HCO3-) reducing its availability for shell-building. It also releases hydrogen ions (H⁺) flooding the buffering system and increasing the acidity of the seas. This is what is known as ‘ocean acidification’.

In October 2008 a meeting of distinguished marine scientists meeting in Monaco signed “The Monaco Declaration” expressing their concern about ocean acidification. One of their concerns was that ocean acidification could slow down or even stop the process whereby marine animals build their shells. The shells of marine animals are mostly made from calcium carbonate, the same material found in chalk and limestone rocks. Calcium carbonate dissolves in acid. So if the seas become to acidic, then animals (such as the tiny single-celled coccolithophore algae pictured on the top left or the wide range of corals, crabs, oysters, clams and shellfish of all kinds pictured on the bottom left) will find it much harder to build shells and protect themselves.

As yet, the oceans of the world are still alkaline, but scientists have noticed minute changes that show the seas are becoming more acidic. The Monaco scientists believe that this is due to the increased amount of carbon dioxide in the atmosphere produced by human activities such as the burning of fossil fuels such as gas, coal and petrol, although volcanoes – both above and below the sea – produce huge amounts of carbon dioxide as well.

To guard against ocean acidification, the human race needs to reduce the amount of carbon dioxide it releases into the atmosphere. You can play your part in this by using less plastic and recycling that which you throw away, by reducing the amount of petrol you use by cycling to work or using public transport, and by switching to ‘clean’ types of electricity generation such as wind power.

Useful link:  

http://bioacid.ifm-geomar.de